Haunted pregnancy

I've posted before about some strange experiences while pregnant and a lot of people suggested it was because you can be sensitive to spirits while pregnant. I never really believe in anything like that until recently and feel a little crazy. My husband works nights so I'm home from 8 pm until 6 am. I have 2 dogs but they usually sleep in our finished basement because it's cooler than our second floor where the bedrooms are. I've started to sleep with the bedroom door closed to trap in the A.C. but it's never locked so my husband can climb into bed without waking me up. Both of us are cold weather people who like to sleep under blankets so the house is usually chilly and we live near an airport so the windows are almost always closed. I'm 36 weeks pregnant so I have been a light sleeper. Last night I was awake enough to roll myself onto my other side which takes a little effort on a memory foam mattress. As soon as I closed my eyes I hear a knock on my bedroom door as clear as day. Even freaking out it took me a few minutes to climb out of bed, lock the door, and grab my gun. I started to try to listen for footsteps or breathing or something until I notice the noise outside. My window was opened but the blinds were still drawn. I don't remember waking up to open the window and with the a.c. running I wouldn't have. it also would have taken a lot of effort to get out of bed so I would have remembered. The window isnt easily accessible from the ground and the screen was still there. If someone climbed in why would they knock on the outside of my bedroom door?I stayed up the rest of the night until my husband came home. i feel like im going crazy.